function plotEllipse(center, radius, ndiv)
%PLOTELLIPSE 
    if nargin <= 2
        ndiv = 128;
    end
    center = reshape(center, 1, 2);
    radius = reshape(radius, 1, 2);
    t = linspace(0, 2*pi, ndiv)';
    x = [cos(t) sin(t)] .* radius + center;
    plot(x(:,1), x(:,2), 'k-', 'LineWidth', 2);
end

